Discoloration in non-vital teeth is often a consequence of endodontic root canal treatment and is also observed in traumatized teeth causing a loss of pulpal vitality. Root canal therapy may cause the treated teeth to darken with time and appear grey in contrast to the normally lighter adjacent dentition. Vital teeth may become stained due to tetracycline prescribed for the mother in her third trimester of pregnancy. As a result such patients may develop a brown or yellow mottled stained appearance in the anterior incisors. Other sources of stains in teeth may come from drinking water with a high content of minerals such as fluoride or iron. These intrinsic stains are not able to be removed by conventional prophylaxis treatments.
One method for treating the discoloration of teeth is bleaching. Bleaching is currently practiced by applying a concentrated hydrogen peroxide solution to the stained tooth and heating the tooth so treated with a bleaching instrument such as an electrically heated metal tip. A bleaching agent of concentrated peroxide solution such as "superoxol" is commercially available for this purpose. Superoxol is a 30 percent solution by weight of hydrogen peroxide in distilled water. The heated metal tip operates much like a soldering iron to raise the tooth to a temperature in the neighborhood of 120 to 140 degrees F. This temperature activates the peroxide solution accelerating the generation of free radicals which enhances the bleaching effect.
Alternatively, a high intensity lamp providing infrared heating energy is used also at approximately 12 inches from the patient's face to heat the area where the tooth is being treated for bleaching.
Existing methods of bleaching have many limitations. The metal tip of the bleaching unit contacts the tooth poorly and does not provide uniform heating of the tooth. There is also an inherent danger of burning adjacent soft tissues and electrical shock. The bleaching lamp produces heat that is so intense that substantial danger exists to the soft tissue which may suffer burns and/or discomfort. Injuries to the adjacent teeth may also occur, due to the large area of radiation.